Buckthorn oblivion

We put up the fence in our backyard 17 or 18 years ago, when our two oldest kids were little and the other two hadn’t come along yet. Our property extends to the bottom of the slope behind the fence, but since the fence went up I’ve mostly ignored the horticultural goings-on back there.

So, there’s this plant called buckthorn, Rhamnus cathartica, an ecological threat in Minnesota and much of the rest of the midwest. You may have heard of it. I’d certainly heard of buckthorn, too, but most of what I heard mentioned its invasiveness in natural areas. I don’t usually think of my suburban yard as a natural area, so I didn’t pay much attention.

Fast-forward through several clueless, happy years to 2016, when I realized that all of those little seedlings I was weeding out of my flower beds were buckthorn. Where were they coming from? Probably from the 15-foot-high buckthorn thicket that was steadily growing behind the fence.

Most of the greenery behind the fence is invasive buckthorn

About 80% of the lovely greenery visible behind the fence is buckthorn. Here’s what it looks like up close:

Our invasive buckthorn thicket

If there was ever any sort of vegetative ground layer, it’s gone for now. I’ve spent some time over the past few days beginning to cut back this thicket. I’m using this method (scroll down to the subsection entitled “Light weapons and a long timeline”). I already had Trimec in the shed. I ordered the blue dye and sponge applicator bottle from Amazon.

Buckthorn fighting tools

Treated buckthorn stumps (the dye faded quite a bit in last night’s rain):

Herbicide-painted buckthorn stumps

Here’s my brush pile so far (plus more waiting to be retrieved from behind the fence):

Buckthorn brush pile

It’s a big chore, but I’m looking forward to seeing what shows up (besides lots more buckthorn seedlings) once some dappled sunlight can reach the ground again. I’ll probably also toss some native savanna/woodland seeds back there to help things along. I’ll post an update or two down the road.

 

Back yard progress report #2

It’s late July. We’ve installed the edging around our lawn oval, taken up about half of the sod outside the oval, and cut down the Amur maple in front of the fence.

Back yard progress report

Looks kind of awful right now, but there is a plan, really!

1. The yard waste bin is a permanent feature for now. Oh, well.

2a. The freshly cut Amur maple snag sticks out like a sore thumb, but it will blend in once it weathers a little and is surrounded by plantings.

2b. The dead Amur maple branches will go away soon.

Back yard progress report with labels

3. The pile of buckthorn should be going away soon, although there’s lots more to cut behind the fence.

4. Need to do some lawn re-seeding this fall. (It was patchy before we started trampling all over it to cut down trees and lay edgers.)

5a, 5b, and 5c. The main issue right now is that cutting down the Amur maple in front of the fence revealed just how bare our evergreen trunks are (two white spruces and a white pine). There’s also another Amur behind the fence (5d) that should go. I’ve asked a couple of tree services to come out and give us their advice.

Seems we’ve also got weedy white mulberry, Siberian elm, and an ash. We’ll have the ash taken down this fall while it’s still healthy. (Apparently it costs a lot more to have one taken down once it’s been hit by emerald ash borer, which is, apparently, inevitable.) We might take down the elm, which is leaning quite a bit, and the second Amur maple. One of the arborists thought there was a good chance the pine trees would fill in, at least a little, now that some sun can reach the trunks. Here’s hoping!

 

How to Be a Good Host (to caterpillars and other creepy-crawlies)

I mentioned in a previous post that I only recently learned that my practice of carting away leaves and old plant stems in the fall is likely contributing to the decline of the local butterfly population (see “Life in the Leaf Litter,” “Six reasons to NOT clean up the garden this fall,” and the related “4 Reasons Not to Rush the Spring Garden Cleanup”). This post is intended to provide links to more information on the topic of host plants for local fauna.

Red admiral on coneflower

First, some terminology.

“A [North American] native plant species is one that occurs naturally in a particular region, ecosystem, and/or habitat and was present prior to European settlement” (definition from Wild Ones).

A native plant grown from seeds or divisions is a straight species native plant.

A nativar is a cultivar of a native plant. (A cultivar is a plant type produced by selective breeding.) Plants are selected for reproduction on the basis of certain characteristics “to the exclusion of the inherent variation found in nature” (Wild Ones).

An obligate larval host plant is a plant that is required by an insect species. The adults might take nectar from a variety of plants, but they will lay their eggs on, and the larvae will feed on, only one or a few species (e.g., monarchs and milkweeds).

According to a recent article in the Star Tribune, planting “for the express purpose of feeding insects” is “a seismic shift in gardening.” The article provides a short list of Minnesota butterflies and their preferred host plants.

A post from the University of Minnesota Extension talks specifically about little bluestem (Schizachyrium scoparium) and the butterfly larvae known to feed on this native grass, including Dakota skippers and several other species of skippers. Interestingly, the only photo in the post shows a cultivar of little bluestem rather than the straight species.

Are cultivars/nativars as useful to wildlife as straight species? For some opinions on this topic see this article from the Rochester Post Bulletin and this from the University of Missouri Extension, both positive. On the more negative end of the spectrum, see this position statement from the Wild Ones, this article from the National Wildlife Federation, and this from EcoBeneficial.

To learn more about host plants other than milkweeds, start with the Native Plant Finder from the National Wildlife Federation, this article from Minnesota Gardener Magazine, and this list from the U of MN Extension. It’s a short list, but additional links and sources are noted.

If you’re more interested in birds than butterflies, note that “96 percent of all birds need insects as part of their diets at some point in their lives – even hummingbirds. … [H]ummingbirds feed their young a certain kind of native bee, and that bee feeds on a native plant: New Jersey tea (Ceanothus americanus). It’s a 3-foot tall shrub with white flowers that bloom from June through August” (quote from the Minnesota Gardener article in the previous paragraph).

Many of the plants mentioned in the sources listed above are readily available from native plant nurseries. Others are harder to come by. I read in Native Plants of the Midwest by Alan Branhagen that Canada plums “host so many creatures that their foliage can look tattered by midsummer.” Branhagen adds: “The gorgeous flowering cultivar ‘Princess Kay’ has been selected from wild Minnesota stock for superb double flowers equally as exquisite as any oriental flowering cherry but providing no nectar for pollinators” (p. 172).

I thought it would be nice to tuck one of these plants into a corner of my yard, but finding straight species Prunus nigra isn’t easy. ‘Princess Kay’ is available from several nurseries, but the only source of non-cultivar Canada plums seems to be seeds from Gardens North. Do I want to grow a plum tree from seed? As the old saying goes, the best time to plant a tree was twenty years ago. When their seed sales re-open in September, I may just send away for a packet.